The present invention relates to methods and apparatus for vector transmission.
Previously, various standards were specified for the encoding of multimedia information (e.g., video information or audio information). An example of such a standard is the image coding standard MPEG4 [3]. Such common standards have allowed the availability of increasing amounts of multimedia information. To make this information available to users, it is necessary to index this multimedia information.
Indexing is normally carried out by descriptors, as they are called, that describe features of multimedia information. Examples of such features are the color distribution or brightness distribution of a digitized image. These descriptors are frequently histogram based (i.e., a frequency of a value of a feature to be described is determined). Such a histogram in the context of a description of a color distribution of a digitized image is known. With this histogram, a color histogram, a frequency is described, with which a specific color value or color range occurs as an image element in an image. Because such a histogram normally has many entries, a comparison of such histograms is expensive. Furthermore, adjacent entries frequently have similar values.
Furthermore, the transformation of histograms is known, such as using a Haar wavelet transformation.
FIG. 2 shows an example of the use of a Haar wavelet transformation (200) on a one-dimensional 4-bin histogram, (i.e., a histogram with four frequency entries). By means of this transformation (200), that is a combination of specified arithmetic operations (i.e., an addition (201) and a subtraction (202)), four entries of the 4-bin histogram—a Value Bin 0 (210), a Value Bin 1 (220), a Value Bin 2 (230), and a Value Bin 3 (240)—are depicted, as shown in FIG. 2, on four Haar wavelet coefficients—a Haar Coeff Index 0 (250), a Haar Coeff Index 1 (260), a Haar Coeff Index 2 (270), and a Haar Coeff Index 3 (280).
The Haar wavelet coefficients are quantized and binarized (i.e., each quantized Haar wavelet coefficient is converted to a corresponding binary number or digit string of binary digits 0 and 1 each with a fixed bit length that can be specified and then encoded to form a bit data stream). This bit data stream is compared with a comparison bit data stream that was encoded in a corresponding manner and also describes a histogram.
By means of this procedure, it is possible to compare two histograms by using their associated bit data streams, without inverse transformation of the bit data streams back to the associated histograms.
FIG. 3 illustrates an example schematic showing a procedure for encoding. FIG. 3 shows a bit level representation (300) of four binarized, quantized Haar wavelet coefficients (301 to 304), that have seven bit levels (301 to 316). With this encoding (320), the four Haar wavelet coefficients (301 to 304) are entered in succession, each corresponding to a reducing bit priority of the associated binary digits in the bit data stream (350). This is achieved in that with the encoding (320) of the Haar wavelet coefficients (301 to 304), the binary digit of the associated most significant bit level, called a most significant bit (MSB) (331), is first entered in the bit data stream (350). As the last bit to be encoded of the particular Haar wavelet coefficients (301 to 304), the binary digit of the lowest order bit level (i.e., 0 bit level (301)), called a least significant bit (LSB) 332, is entered in the bit data stream (350).
The result of this procedure is that the binary digits of coded Haar wavelet coefficient (361 to 367) are entered in the bit data stream (350) separately from those of the succeeding encoded Haar wavelet coefficients (371 to 374). The transmission of such a bit data stream to a receiver and its comparison in the receiver with a further bit data stream encoded in the same way, that represents a histogram to be compared, is also known in the art. However, this known procedure has the disadvantage that information encoded in the bit data stream is transmitted in such a way that unnecessary information also has to be transmitted in the bit data stream for a rough comparison of the two histograms. The result is that the transmission bandwidth used for such a comparison cannot be reduced.